1. Field of the Invention
The present invention generally relates to a driving device for a toner cartridge, and more particularly to a built-in driving device for a toner cartridge for use in a printing apparatus, such as a laser printer, a copy machine, a xerographic device, etc.
2. The Prior Arts
FIG. 1 is a schematic view showing a conventional transmission mechanism for a toner cartridge that is compatible with laser printers, photocopiers, xerographic devices, etc. As shown, the conventional transmission mechanism 3 is provided at one side of a toner cartridge body 20, and is adapted to transmit movement to a gear assembly disposed inside of the cartridge body 20 for performing various printing operations. More specifically, the transmission mechanism 3 includes a transmission tenon 32 provided at one side of the cartridge body 20. The transmission tenon 32 includes a coupling end 321 having a polygonal shape and adapted to couple with a transmission sleeve 31 provided in a printing apparatus, such as a laser printer or a xerographic device. The transmission sleeve 31 has a coupling groove 311 that is adapted to engage with the coupling end 321 to transmit movement to the component parts in the toner cartridge for performing various printing actions.
When the toner cartridge is going to be mounted in the printing apparatus, the triangular coupling end 321 has to be aligned with the coupling groove 311 to properly engage the transmission tenon 32 with the transmission sleeve 31. If the triangular coupling end 321 is not aligned with the coupling groove 311, it needs to rotate the triangular coupling end 321 to be aligned with the coupling groove 311. However, when the triangular coupling end 321 is rotated, the triangular coupling end 321 of the transmission tenon 32 is pressed against the transmission sleeve 31, which results in wear. Moreover, the cross section of the triangular coupling end 321 is relatively large, which results in more wear. Therefore, it is inconvenient to replace the toner cartridge and it is also troublesome to solve the malfunction. In addition, because the shape of the coupling end 321 is triangle, the maximum angle, which the coupling end 321 needs to rotate to be aligned with the coupling sleeve 311, is 120 degrees. As a result, before the coupling end 321 is rotated to an engaging position, substantial frictional wear may occur during rotation, which increases the occurrence of damage in use, increases the driving load of the printing apparatus, and makes it less stable in operation. In addition, the transmission mechanism 3 of the printing apparatus uses gears for transmission. The toner cartridge is usually made of plastic that is not stiff enough. Owing to the complex gear engagement and the material property, the driving force of the printing apparatus can not be fully transmitted to the cartridge, adversely affecting the printing quality.